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OSDLR_EL1, OS Double Lock Register

The OSDLR_EL1 characteristics are:

Purpose

Used to control the OS Double Lock.

Configuration

AArch64 System register OSDLR_EL1 bits [31:0] are architecturally mapped to AArch32 System register DBGOSDLR[31:0] .

This register is in the Warm reset domain. Some or all RW fields of this register have defined reset values. On a Warm or Cold reset these apply only if the PE resets into an Exception level that is using AArch64. Otherwise, on a Warm or Cold reset RW fields in this register reset to architecturally UNKNOWN values.

Attributes

OSDLR_EL1 is a 64-bit register.

Field descriptions

The OSDLR_EL1 bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
RES0
RES0DLK
313029282726252423222120191817161514131211109876543210

Bits [63:1]

Reserved, RES0.

DLK, bit [0]

When ARMv8.0-DoubleLock is implemented:

OS Double Lock control bit.

DLKMeaning
0b0

OS Double Lock unlocked.

0b1

OS Double Lock locked, if DBGPRCR_EL1.CORENPDRQ (Core no powerdown request) bit is set to 0 and the PE is in Non-debug state.

On a Warm reset, this field resets to 0.


Otherwise:

Reserved, RAZ/WI.

Accessing the OSDLR_EL1

Accesses to this register use the following encodings:

MRS <Xt>, OSDLR_EL1

op0op1CRnCRmop2
0b100b0000b00010b00110b100
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.<TDE,TDOSA> != '00' && (IsFeatureImplemented(ARMv8.0-DoubleLock) || boolean IMPLEMENTATION_DEFINED "Trapped by MDCR_EL2.TDOSA") then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDOSA == '1' && (IsFeatureImplemented(ARMv8.0-DoubleLock) || boolean IMPLEMENTATION_DEFINED "Trapped by MDCR_EL3.TDOSA") then
        AArch64.SystemAccessTrap(EL3, 0x18);
    else
        return OSDLR_EL1;
elsif PSTATE.EL == EL2 then
    if HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDOSA == '1' && (IsFeatureImplemented(ARMv8.0-DoubleLock) || boolean IMPLEMENTATION_DEFINED "Trapped by MDCR_EL3.TDOSA") then
        AArch64.SystemAccessTrap(EL3, 0x18);
    else
        return OSDLR_EL1;
elsif PSTATE.EL == EL3 then
    return OSDLR_EL1;
              

MSR OSDLR_EL1, <Xt>

op0op1CRnCRmop2
0b100b0000b00010b00110b100
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.<TDE,TDOSA> != '00' && (IsFeatureImplemented(ARMv8.0-DoubleLock) || boolean IMPLEMENTATION_DEFINED "Trapped by MDCR_EL2.TDOSA") then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDOSA == '1' && (IsFeatureImplemented(ARMv8.0-DoubleLock) || boolean IMPLEMENTATION_DEFINED "Trapped by MDCR_EL3.TDOSA") then
        AArch64.SystemAccessTrap(EL3, 0x18);
    else
        OSDLR_EL1 = X[t];
elsif PSTATE.EL == EL2 then
    if HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDOSA == '1' && (IsFeatureImplemented(ARMv8.0-DoubleLock) || boolean IMPLEMENTATION_DEFINED "Trapped by MDCR_EL3.TDOSA") then
        AArch64.SystemAccessTrap(EL3, 0x18);
    else
        OSDLR_EL1 = X[t];
elsif PSTATE.EL == EL3 then
    OSDLR_EL1 = X[t];
              


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